Horizontal variability in air temperature over time within a maize inter-row

Many processes under study in the fields of ecophysiology and epidemiology are driven by air temperature, and response to temperature is often represented by a non-linear function. However, a question persists: “which estimate would best account for temperature: the weather station temperature, the average of the vertical profile of air temperature or its 3D distribution within the canopy?” We present experimental results accounting for spatial heterogeneity of air temperature within a maize canopy throughout the crop cycle. Data analysis focused on small-scale variability by studying air temperatures across an inter-row of maize over time at varying heights above the soil. Air temperature was in fact horizontally homogeneous across a maize inter-row at a given height during the growing and senescing period. Thus, measured or simulated vertical profiles adequately reflect the spatial distribution of air temperature within a canopy. These conclusions were fully valid for nighttime periods. For daytime periods, they were valid except at the canopy core height around noon on a few low wind, sunny days. We discuss the few cases of horizontally heterogeneous air temperature as well as the factors that favored them.